Post subject: Re: Identification of Clear High-RI crystal
Posted: Fri Sep 06, 2019 9:22 pm
Gold Member
Joined: Sun Jun 28, 2009 9:56 am Posts: 1284
Let's just start with classical gemological testing:
-observation of surface features and inclusions under magnification (loupe/microscope) -in the process, also check for doubling (of broken angles, inclusions and/or surface features), -confirm exact SG of the material, with two decimals (let's note that a digital scale accurate to 0.01g will work fine provided that the stone weighs at least 3g), -give a few tries at a spot reading with the refractometer, just to confirm that the material is indeed unreadable (I know it is supposed to be >1.78 and thus unreadable but let's just make sure) -then see if you can try and get the optical character of the material using polariscope+conoscope (note that a polariscope can be built from a broken LCD screen, and a triplet loupe can be used as a conoscope). -check spectrum (if any) with handheld spectroscope -check LW & SW UV fluorescence (if any) -considering it's a rough, you may also want to check hardness (first try against a plate of copper, if copper gets scratched then try against glass, and if glass gets scratched then try against a polished piece of quartz).
Oh and don't forget to provide us with a clean picture (properly focused, in daylight, over a white background)
SG was about 4.5 LWUV reaction - weak pink fluorescence Not able to get SG reading at all - even polished a little flat on it. So above 1.8 No reaction in polariscope
After putting all this together, I came to the conclusion it's clear YAG. Too bad, I was hoping that it was Lithium Niobate But clear YAG isn't so bad also.
-Allan
_________________ Allan Aoyama http://www.omnifaceter.net <- Omnifaceter is back online!
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